JPH09109816A - Air bag door structure for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lightweight air bag door structure for vehicles which meets the physical properties required for an air bag door part and a room side member, and which is excellent in safety and formability. SOLUTION: A room side member 10 having an air bag door part 12 integrally formed with the general surface is made of a polypropylene resin in which the tensile elongation is 300% or more, the bending elastic modulus is 20000kgf/ cm<2> or more, the heat deformation temperature is 120 deg.C or more, and the Izod impact strength at 23 deg.C is 15kg.cm/cm or more. An air bag door reinforcing member 20 is made of olefinic elastomer in which the bending elastic modulus is 3000kgf/cm<2> and the Izod impact strength (-40 deg.C) is 20 kg.cm/cm, and is integrally joined to the back face of the air bag door part 12 when the room side member 10 is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle air bag system, and more particularly to an air bag door structure thereof.

[0002]

2. Description of the Related Art Generally, in an airbag device provided on a passenger side of a vehicle, a folded airbag is housed in an airbag case together with an actuating device, and is housed in a passenger compartment member in front of the passenger seat. There is. On the other hand, a deployment opening for an airbag is provided at a predetermined position of the vehicle-cabin-side member, and the deployment opening is covered with an airbag door in a normal state. When the vehicle receives a large impact due to a collision or the like, the airbag accommodated in the airbag case is inflated, the airbag door is pushed open from the inside, and the airbag is introduced into the vehicle compartment through the deployment opening. It is designed to be deployed.

In such an air bag door structure, the air bag door is generally molded separately, fitted into a deployment opening formed in the vehicle interior side member, and attached to the air bag case via a hinge or the like. Target. However, this mounting work is not easy at all, and the cost of such mounting work cannot be ignored. Moreover, this work itself is not only complicated, but it is also difficult to mount it accurately. In the past, the clearance between the airbag door and the deployment opening was increased to improve the efficiency of the airbag door installation work. There was a problem of impairing the appearance.

Therefore, in recent years, FIG. 11 and FIG.
As shown in FIG. 5, the airbag door portion 81 is now integrally formed on the general surface 82 of the vehicle interior side member 80. Reference numeral 90 is an airbag device, C is an airbag case, A is an airbag, and I is an actuating device. The airbag door portion 81 has a planned breakage portion 83 formed of a fragile portion such as a V groove or a slit at a predetermined position on the back surface of the passenger compartment side member 80.
Are formed in a substantially U-shape or a U-shape so that they are integrally formed. Then, a reinforcing plate 84 having a mounting portion 85 is integrally mounted on the back surface side of the airbag door portion 81, and the mounting portion 85 is connected to the airbag case C. Reference numeral 86 is an airbag case attachment portion that is hung from the rear surface of the passenger compartment side member 80 and fixed to the airbag case C. When the airbag A is deployed, as shown in FIG. 13, the inflation pressure pushes the airbag door portion 81 from the rear surface side through the reinforcing plate 84, and the portion to be broken 8
3 is broken, and the airbag door portion 81 is opened.

In this structure, if the reinforcing plate 84 is made of metal, the passenger compartment member 80 becomes heavy and the mounting work becomes difficult. Therefore, it has been proposed that the reinforcing plate 84 be made of hard plastic and be integrally formed on the rear surface of the passenger compartment member 80. In this way, the vehicle interior side member having the two-layer structure of the airbag door portion having the resin forming the vehicle interior side member and the resin forming the reinforcing plate is often molded as follows. That is, a method in which a preformed reinforcing plate is placed in a mold during molding of the vehicle interior side member and integrated with the vehicle interior side member, and the reinforcing plate and the vehicle interior side member having an airbag door portion are simultaneously injected. It is so-called double injection molding for molding.

However, in the case of such a structure, the resin material of each layer used is required to have the following physical properties. First, there is the adhesive strength between the resin material forming the passenger compartment member and the resin material forming the reinforcing plate. Also,
Secondly, when the reinforcing plate is used as an insert when molding the passenger compartment side member, in order not to impair the formability of the passenger compartment side member, the reinforcing plate placed in the mold is the general surface of the passenger compartment side member. It must have a rigidity that does not easily deform even when subjected to the shearing force of the molten resin for molding. Furthermore, thirdly, there is little difference in the elongation characteristics with respect to stress between the resin materials forming both layers. This is because if there is a large difference in the elongation of the two layers of resin material, when the airbag door section is deformed due to the expansion of the airbag, etc., one layer will not be able to follow the deformation and will be significantly destroyed. This is because fragments and the like may be scattered.

Further, the resin material for the vehicle interior side member is sufficiently stretched and rigid enough to cover cracks and the like when the airbag door is deployed, and is deformed due to temperature rise in the vehicle interior. High heat resistance is required so that it does not occur. Further, the resin material on the side of the reinforcing plate is required to have impact strength capable of withstanding use at low temperatures.

At present, the main resin materials used as vehicle interior side members are polypropylene resin (PP in the table), modified polyphenylene oxide (modified PPO in the table), glass fiber reinforced acrylonitrile-styrene copolymer (table Medium ASG). Further, resin materials used for airbag doors include olefin elastomers (TPO in the table) and styrene elastomers (TP in the table).
S), polyester elastomers (TPEE in the table) and other thermoplastic elastomers, as well as polymer alloys of polyphenylene oxide and 6-nylon (PA / P in the table).
PO) is used. The present inventors have examined the adhesiveness of these various resins having physical properties suitable for a vehicle interior side member or an airbag door. The results are shown in the table below.

[0009]

As a result, it has been found that the combination of the PP resin and the TPO resin exhibits the best adhesiveness. Then, a further examination was carried out by constructing a member on the vehicle interior side having an airbag door portion using these resins, and in the case of combining the resins having predetermined physical properties, the adhesiveness of both layers was good and moldability was improved. The present invention has finally been accomplished, and it has been found that it has excellent rigidity, high rigidity and heat deformation temperature, and exhibits excellent physical properties with respect to good impact strength at low temperatures.

[0011]

SUMMARY OF THE INVENTION The present invention provides a lightweight airbag door structure for a vehicle that satisfies various physical properties required for an airbag door portion and a vehicle interior side member, is excellent in safety, and has good moldability. It is the one we are trying to provide.

[0012]

That is, the present invention provides:
A passenger compartment member having an airbag door portion integrally formed with a general surface, and an airbag door reinforcing member integrally joined to the back surface of the airbag door portion at the time of molding the passenger compartment member, The passenger compartment member has a JIS-K7113 tensile elongation of more than 300% and a JIS-K7203 flexural modulus of more than 20000 kgf / cm ^2.
The heat distortion temperature of IS-K7207 is higher than 120 ° C,
JIS-K7110 is made of polypropylene resin having an Izod impact strength (23 ° C.) of more than 15 kg · cm / cm, and the airbag door reinforcing member has a flexural modulus of 3000 kgf of JIS-K7203.
/ Cm ^{2 and} an Izod impact strength (-40 ° C.) of JIS-K7110 of more than 20 kg · cm / cm.

[0013]

According to this structure, since the airbag door portion is formed integrally with the general surface, not only the appearance of the passenger compartment side member becomes very good, but also the conventional single-layered member has the same appearance as the passenger compartment side member. It was difficult to satisfy all the required physical properties for the airbag door part, but by adopting such a two-layer structure, the physical properties of the cabin side member and the airbag door reinforcing member complement each other, and as a whole Physical properties required for the passenger compartment member and the airbag door can be retained.

Furthermore, since the passenger compartment member is made of polypropylene resin and the airbag door reinforcing member is made of olefin elastomer, the adhesiveness between the two members is extremely good as described above, and the molding accuracy and efficiency are improved. Is extremely good. Moreover, since the vehicle interior side member and the airbag door reinforcing member are all made of resin, they are lightweight and easy to install.

In the present invention, the physical properties of the polypropylene resin constituting the vehicle interior side member are set so that the tensile elongation of JIS-K7113 is greater than 300% when the airbag door is deformed by the airbag expansion. This is because the deformation of the passenger compartment side member is made to follow the deformation of the airbag door reinforcing member and the opening of the airbag door reinforcement member to prevent damage to the passenger compartment side member side and protect the occupant. And JIS-K7110
Izod impact strength (23 ℃) of 15kg ・ cm / c
The reason for making it larger than m is to prevent cracking of the member on the passenger compartment side when the airbag door is deployed at room temperature.
Also, the flexural modulus of JIS-K7203 is 20000k.
The reason why it is set to be larger than gf / cm ² is to impart sufficient shape retention to the vehicle interior member. Furthermore, JIS-K7
The heat deformation temperature of 207 is set to be higher than 120 ° C. in order to prevent the deformation even when the passenger compartment side member becomes high in temperature due to direct sunlight during parking in summer.

In the present invention, the physical properties of the olefin-based elastomer constituting the airbag door reinforcing member are defined by JI
Bending elastic modulus of S-K7203 is 3000 kgf / cm ²
The reason for making it larger is to give the airbag door reinforcing member self-shape retention against the shearing force of the molten resin at the time of molding the vehicle interior side member, and the Izod impact strength (-40 ° C) of JIS-K7110. Is set to be larger than 20 kg · cm / cm in order to prevent the attachment portion to the airbag case from being damaged when the airbag is deployed at low temperature.

The polypropylene resin used for the vehicle interior side member is not particularly limited as long as it satisfies the above-mentioned physical properties, and an appropriate amount of other thermoplastic resin or filler may be blended.

As the olefin elastomer used for the airbag door reinforcing member, there is a blend of polypropylene and ethylene-propylene copolymer rubber, or a blend obtained by dynamically vulcanizing the blend.

The polypropylene resin and the olefin elastomer may be appropriately added with additives that do not impair the desired physical properties. Examples of the additives include antioxidants, ultraviolet absorbers, fluidity improvers, and reinforcing materials such as talc and fibers.

[0020]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below with reference to the accompanying drawings. 1 is an exploded perspective view showing an essential part of the structure of the present invention, FIG. 2 is a sectional view taken along line 2-2 of FIG. 1, and FIG.
1 is a sectional view taken along line 3-3 of FIG. 1, FIG. 4 is a sectional view showing another example of the portion to be broken, FIG. 5 is a sectional view showing another example, and FIG. 6 is another example of the present invention. FIG. 7 is an exploded perspective view, FIG. 7 is a sectional view taken along line 7-7 of FIG. 6, FIG. 8 is a sectional view taken along line 8-8 of FIG. 6, and FIG. 9 is a perspective view showing another example of an airbag door reinforcing member. 10 is a perspective view showing another example of the airbag door reinforcing member.

As shown in FIG. 1 and FIGS. 2 and 3 which are cross-sectional views thereof, the vehicle airbag door structure of the present invention comprises a passenger compartment member 10 and an airbag door reinforcing member 20. The vehicle interior side member 10 has an instrument panel-shaped general surface 11 and an airbag door portion 12 integrally formed at a predetermined position of the general surface 11. As described above, the passenger compartment member 10 has a tensile elongation of JIS-K7113 of more than 300%, a bending elastic modulus of JIS-K7203 of more than 20000 kgf / cm ² , and a heat deformation temperature of JIS-K7207. It is composed of a polypropylene resin having a Izod impact strength (23 ° C.) of JIS-K7110 of more than 120 ° C. and more than 15 kg · cm / cm. Thus, by forming the vehicle interior member 10 from a resin having a high impact strength, a high thermal deformation temperature, and good elongation characteristics, the impact due to normal use, the temperature increase in the vehicle interior, or the expansion of the airbag door portion. Deformation at the time of opening, deformation due to impact, and damage are prevented.

The airbag door reinforcing member 20 has a body portion 21.
And a mounting portion 22. The main body portion 21 has a shape substantially equal to the shape of the airbag door portion 12, and the mounting portion 22 is integrally erected on one side of the main body portion 21 via a hinge portion 23, so that the airbag portion is provided. Fixed part C of case C
Mounting holes 24 through which bolts for fixing to 1 are inserted
Is provided. This airbag door reinforcing member 20
The main body portion 21 is integrally joined to the back surface side of the airbag door portion 12 when the passenger compartment member 10 is molded.

The airbag door reinforcing member 20 is made of a resin material having the following physical properties. That is, the flexural modulus of JIS-K7203 is 3000 kgf.
/ Cm ^{2 and} an Izod impact strength according to JIS-K7110 of more than 20 kg · cm / cm (−40 ° C.).

In the present embodiment, the airbag door portion 1
Reference numeral 2 denotes a to-be-ruptured portion 1 formed on the rear surface side of the passenger compartment member 10.
It is partitioned by 3. This planned breaking portion 13 is
The airbag door reinforcing member 20 is formed of a V-shaped groove formed in a substantially U-shape along the outer peripheral shape of the main body portion 21 except the attachment portion 22 side. This breakable part 13
Receives the pressure when the airbag is inflated and ruptures first,
This is to promote a smooth deployment opening of the airbag door portion 12. The breakable portion 13 may be a U groove, a slit, or the like, or may be discontinuously provided in a perforated shape.

The portion to be broken is provided on the back surface of the vehicle compartment side member as described above, or on the airbag door reinforcing member,
It may be provided on the front surface side of the passenger compartment member. FIG. 4 and FIG. 5 show an example thereof. In FIG. 4, the size of the main body of the airbag door reinforcing member is made slightly larger than the size of the airbag door, and the portion to be broken is formed at a predetermined position on the main body. Reference numeral 30 is a vehicle interior side member, 31 is an airbag door portion, 32 is an airbag door reinforcing member, 33 is a mounting portion, and 34 is a breakable portion. Further, FIG. 5 shows an example in which the planned breakage portion is also provided on the front surface side of the vehicle interior side member. Code 35
Is a passenger compartment member, 36 is an airbag door portion, 37 is an airbag door reinforcing member, 38 is a mounting portion, and 39 is a breakable portion.

In this structure, the airbag door reinforcing member 20 is integrally joined with the resin forming the passenger compartment side member at the time of molding the passenger compartment side member 10. As a result, the airbag reinforcing member is integrally formed on the back surface of the airbag door portion at the same time when the passenger compartment member is molded. Further, the passenger compartment side member and the airbag door reinforcing member can be simultaneously and integrally formed by a known double injection method. In the present embodiment, an example is shown in which separate molding is performed in advance by injection molding or the like, and when the passenger compartment side member is molded, it is arranged as an insert at a predetermined position in the molding die and molded.

6 to 8 show another example of the present invention. In the airbag door structure shown here, the airbag door reinforcing member 40 includes a main body portion 41 and the main body portion 4.
The mounting portion 42 is provided upright from the four sides of No. 1, and the mounting portion 42 is composed of a hinge side mounting portion 42A and an open side mounting portion 42B. Hinge side mounting part 42A
Has an attachment hole 43A extending from one side of the main body 41 and fixed to the airbag case C. Also,
The open side mounting portion 42B is integrally extended from the remaining three sides of the main body portion 41 in a U shape as shown in the figure. Reference numeral 43
B is a mounting hole for the airbag case C. Then, as shown in FIGS. 5 and 6, a V-groove-like breakable portion 44 is formed along the boundary between the main body portion 41 and the open side attachment portion 42B. This airbag door reinforcement member 4
In No. 0, the main body 41 is integrally joined to the passenger compartment member 50.

According to this structure, the airbag case C and the passenger compartment side member 50 are firmly coupled, and the gap between the airbag case C and the passenger compartment side member 40 is fixed to the hinge side mounting portion 42A. Since it is covered with the open side mounting portion 42B, the inflation pressure of the airbag (not shown) in the airbag case C is effectively concentrated on the back surface of the airbag door portion 41, so that the breakable portion 44 can be swiftly and quickly. It can be reliably broken.

Further, as described above, when the airbag door reinforcing member is used as an insert and integrally molded with the vehicle cabin side member, the airbag reinforcing member is provided with irregularities or holes to increase its surface area, It is preferable to enhance the integrity of the airbag reinforcing member and the airbag door portion of the vehicle interior side member.
The airbag door reinforcing member 60 shown in FIG. 9 has a large number of recesses 6 formed on the surface of the main body 61 on the side joined to the vehicle interior member.
3 is provided. Reference numeral 62 is a mounting portion.

Furthermore, the airbag door reinforcing member 70 of FIG. 10 is an example in which a large number of through holes 73 are provided in the main body portion 71. Reference numeral 72 is a mounting portion. According to this structure, during molding, the polypropylene resin forming the vehicle interior side member fills the through holes 73, so that the vehicle interior side member and the airbag door reinforcing member 70 are firmly joined.

[0031]

The present invention will be described in more detail with reference to specific examples. First, a polypropylene resin and an olefin elastomer having the physical properties shown in the table below were prepared. [Example 1] Using a resin for an airbag door, an airbag door reinforcing member is previously formed by known injection molding. Then, the reinforcing member for the airbag door is arranged as an insert at a predetermined position in the molding die for the passenger compartment side member, and the resin for the passenger compartment side member is injected to be integrated with the airbag door reinforcing member to the passenger compartment side. The member was molded.

[0032]

As a comparative example, a polypropylene resin and an olefin elastomer were combined in place of and in the above table. [Comparative Example 1] A passenger compartment member was molded in the same manner as in Example 1 except that the olefin elastomer was changed to one having the physical properties shown in the table. [Comparative Example 2] A passenger compartment member was molded in the same manner as in Example 1 except that the polypropylene resin was changed to one having the physical properties shown in the table. [Comparative Example 3] A passenger compartment member was molded in the same manner as in Example 1 except that the polypropylene resin and the olefin elastomer were changed to those shown in and in the table.

[Evaluation Method] The moldability of the vehicle interior side member having the airbag door section when these resin materials were used was observed, and a deployment test of the obtained airbag side section of the vehicle interior side member was performed. I did. The results are shown in the following table. [Moldability] Deformation and warpage of the molded article on the vehicle interior side after demolding were observed. Good molding was evaluated as ◯, and deformation was evaluated as x. [Development test] An airbag case was attached to the airbag reinforcing member of the vehicle interior side member, left for 1 hour in an atmosphere of 23 ° C, and then released from the atmosphere. Thereafter, the airbag was deployed within 1 minute, and the damaged state and the operating state of the airbag door portion and the vehicle interior side member were observed. Evaluation,
When the vehicle interior side member and the airbag door part were cracked and did not operate normally, x was evaluated, and those which operated normally were evaluated as o.

[0035]

[0036]

As shown and described above, according to the vehicle airbag door structure of the present invention, all the physical properties required for the airbag door and the passenger compartment member are satisfied, and the safety is high. Moreover, it is lightweight and can be mounted efficiently. In addition, since the airbag door reinforcing member has a predetermined strength during molding, it is reinforced by the shearing force of the molten resin of the passenger compartment side member, whether it is known insert molding or double injection molding. The member is not deformed or warped, and can be molded extremely easily and reliably.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a main part of the structure of the present invention.

FIG. 2 is a sectional view taken along line 2-2 of FIG.

FIG. 3 is a sectional view taken along line 3-3 in FIG. 1;

FIG. 4 is a cross-sectional view showing another example of the planned breakage portion.

FIG. 5 is a sectional view showing another example of the same.

FIG. 6 is an exploded perspective view showing another example of the present invention.

FIG. 7 is a sectional view taken along line 7-7 in FIG. 6;

8 is a sectional view taken along line 8-8 of FIG.

FIG. 9 is a perspective view showing another example of an airbag door reinforcing member.

FIG. 10 is a perspective view showing another example of the airbag door reinforcing member.

FIG. 11 is a cross-sectional view showing a conventional airbag door structure of a vehicle.

FIG. 12 is a sectional view taken along the line 11-11.

FIG. 13 is a cross-sectional view showing a state when the airbag is deployed.

[Explanation of symbols]

 10 Vehicle Side Member 11 General Surface 12 Airbag Door Part 20 Airbag Reinforcement Member 21 Main Body Part 22 Attachment Part

Claims (1)

[Claims] 1. A passenger compartment member having an airbag door portion integrally formed with a general surface, and an airbag door reinforcement integrally joined to a rear surface side of the airbag door portion when the passenger compartment member is molded. The member on the passenger compartment side has a tensile elongation of 3 according to JIS-K7113.
Is greater than 00%, the flexural modulus of JIS-K7203 is greater than 20000 kgf / cm ² , and JIS-K72
The heat distortion temperature of 07 is higher than 120 ° C, and JIS-K7
The Izod impact strength of 110 (23 ℃) is 15kg ・ c
The airbag door reinforcing member is made of a polypropylene resin larger than m / cm, and has a flexural modulus of JIS-K7203 of more than 3000 kgf / cm ² ,
S-K7110 has Izod impact strength (-40 ° C) of 2
An airbag door structure for a vehicle, which is characterized by being constituted by an olefin-based elastomer of more than 0 kg · cm / cm.